Multiple assignment in one line for atomic bool variables

Given:

class foo {
  std::atomic<bool> a;
  std::atomic<bool> b;
}

Is there any difference between:

void foo::reset() {
  a = false;
  b = false;
}

And:

void foo::reset() {
  a = b = false;
}

Namely, in the second case, can it happen that after b is assigned false, another thread set b to true before b is read to assign its value to a, so that at the end of the instruction the value of a is true?

(This would also imply that the letter version is seemingly less efficient)